Suppose we are scheduling IO requests for Megatron 747 disk

Suppose we are scheduling I/O requests for Megatron 747 disk, and the requests in Figure are made, with the head initially at track 32000. At what time is each request serviced fully

if: We use the elevator algorithm( it is permissible to start moving in either direction at first)

cylinder of request	first time available
8000	0
48000	1
4000	10
40000	20

Solution

Elevator algorithm cylinder of request first time available 1+(32000-8000)/4000+4.3 = 11.3 8000 0 (11.3)+1+(48000-8000)/4000+4.3=26.6 48000 1 (33.9)+1+(40000-4000)/4000+4.3= 48.2 4000 10 (26.6)+1+(48000-4000)/4000+4.3= 33.9 40000 20